Prosecutors say Tyshawn Augustus, 27, killed Young in a sex-for-drugs hookup that devolved into a robbery.

It all ended, prosecutors said, with Young dead and the convicted drug dealer making off with his Fender Stratocaster guitar.

“They were planning to meet for the purpose of engaging in sex for drugs,” Assistant DA James Leeper said, adding that prior to the shooting, the two men had chatted over the phone about the exchange.

“The actual encounter turned out very differently. It turned into a fatal encounter,” Leeper said.

Young’s family sat stoically in the Brooklyn Supreme Court gallery.

“There are no words. I wish they had the death penalty,” said Young’s sister, Allyson Marotta, who dabbed both eyes with a tissue during the trial.

The case against Augustus rests on the phone contact between him and Young, the musician’s DNA that was found under Augustus’ fingernails and the expected testimony of a man who says Augustus recruited him to help with the robbery, prosecutors said.